Hydraulic control system



Feb. 19, 1952 R. DETREZ HYDRAULIC CONTROL SYSTEM Filed Oct. 30, 1945 Patented F eb. 19, 1952 UNITED STATES PATENT OFFICE Application october so, 1945, sentano. '625,599 VIn France November'S, 1944 "control system adapted to control movable parts.

More particularly, this invention relates to an improvement in the system disclosed in my earlier filed co-pending application Serial No. 613,664, filed August 30, 1945, now abandoned.

The principle advanced by said co-pending application embodied controlling of the movement of parts of certain machines by hydraulic pistons actuatingr and locking one another and so arranged that the initiation of movement of the several pistons is possible only when the controlling piston has moved a distance corresponding to the work that it must perform. This mutual controlling and locking of the pistons was effected by rst utilizing the translatory movement of each piston and by providing one or more passages in the piston rods which at the proper moment provided communication with other passages provided in the cylinders to transmit fluid under pressure to distributing valves controlling the pistons to be moved.

In some instances, the passages provided in the piston rods permitted liquid to be driven out of the cylinders. long working stroke of a piston is involved, the length of stroke would require an elongated passage the length of which contributed to the escape of fluid under pressure from the cylinder.

Additionally, when it is necessary that one acf tuating piston initiate the movement of another piston before the forward or return stroke of the first piston is accomplished, the vfact that the movement of said other piston is initiated utilizing a port provided in the piston rod of the actuating piston, results in initiation of the movement of the said other piston on two occasions, first, toward the end of the forward stroke of the actuating piston and again on the beginning of the return stroke thereof or vice versa.

The present invention, therefore. has for ,an object to provide a hydraulic control system vof the type disclosed in said co-pending application but structurally organized so as to eliminate the aforementioned deficiencies attendant with providing passages in the piston rods.

It is an additional object to provide a hydraulic control system in which the control passage providing communication between the source of fluid under pressure and the distributing valves v are embodied in independent members associated with the working pistons and cylinder and including movable means actuated 'in response to .the movement of the pistons.

In accordance with the present invention the Also, in the instance where a a 4 Claims. (Cl. (S0-97) control system comprises a number of similar units each embodying a hydraulic motor, the piston of which has at least one cam member fast to the piston rod orto another member .fixed to `the piston rod. at least one releaser actuated by the cam and a distributor controlling .the hydraulic motor, the said distributor being .controlled in turn by a releaser associated with any one of the units.

This combination which may be utilized for actuating the movable parts of a machine tool or other automatic apparatus rpermits the .following operations, the total effect of which cannot be obained Awith known control systems:

(l) All of the pistons are vinterlocked, so that in a given sequence of movement where the stroke of each piston is conditioned upon the attainment `of a given movement by the preceding piston none of the pisons can initiate its Working stroke so long as the said preceding piston has not accomplished its function.

(2) A given sequence of motion may be .automatically repeated.

A(3.) The speed of movement of all of the pistons, or in other words the speed at which the entire cycle/of movement is performed, can be regulated by means of a .single control valve.

(4) Each piston can initiate the movement .of several other pistons simultaneously and by utilizing yieldable cam members controlling at least one releaser can initiate vthe movement of several -other pistons successively.

(5)1Each piston can control its proper stroke.

`Further and more specic objects will be apparent from vthepfollowing description taken in connection with the accompanying drawing diagrammatically illustrating an embodiment of the invention.

In vthe drawing the control system includes three hydraulic motors reach including driving or working pistonsand .their associated rods a1, b1 .and c1 .reciprocable respectively in cylinders a2, b2 `and e2. Each piston rod has mounted fast thereon the support members am, 1219 and c19 Whichreciprocate with the pistons. 'Ihe ow of .pressure fluid .to the respective .cylinders is controlled by `distributors associated therewith and -including the distributor valves a3, b3, and c3 havingpistons at the opposite ends thereof recip- AIocablein the cylinders a4, b4 .and c4 respectively. Each. of thelast mentioned' cylinders includes a chamber `on opposite sides of the associated valves `and an orifice communicating with the bottomor base ofeach chamber. Likewise associated with the respective hydraulic motors are assacas 3 releasers controlling iiuid ow from the pressure source to the distributors. Each of the releasers embodies a movable member adapted to be actuated in response to the stroke of the working pistons, as will be set forth in detail hereinafter.

On the member or support alf are mounted cam members c2", ya21 and n.22 so arranged as to engage and depress at the proper time plungers i123, c and a27 respectively embodied with releasers n.24, a26 and a2, the depressing of these plungers permitting iiuid to flow through the particular releaser to the distributors in communication with that releaser.

Additional cams are provided on the support members b1g and C19. The cam b2 at the lower edge of support 2219 cooperates with and depresses plunger b23 of the releaser Z224 while support C19 has lower and upper cams c2 and C21 cooperating respectively with the plungers o23 and C21 of the releasers c24 and c28- In the drawing the thick, solid lines denote pressure lines having their origin at a source of pressure constituted by a motor driven pump p drawing working fluid from a tank r which is in communication with the atmosphere and delivers fluid under the control of a shut-oir gate valve l1. The pressure lines P on the delivery side of valve il lead to the releasers and to the distributors. The thick, broken lines denote conduits providing communication between the releasers and the distributors and the line A denotes a return pipe to the reservoir which is at atmospheric pressure. Conduits a6 and a1 provide communication between the distributor cylinder a4 and the opposite ends of the working cylinder a2 and similar arrangements embodying conduits b, b1 and c?, c1 provide communication between the distributors b1, c4 and working cylinders b2, c2. respectively.

The fine, solid lines a9, b9 and o9 denote conduits connecting the distributors ayi and c1 with the return pipe A for evacuating liquid discharged through the distributors by the working pistons.

The ne broken lines am, bu", i115", 1215, C12 and c15 denote conduits through Wwhich liquid travels from the releasers to the return pipe.` The liquid discharged by the upper end of distributing slide valve c3 ows through conduit am", thence through releaser e121 and conduit am". The liquid discharged from the lower end of slide valve b3 ows through conduit Z112', releaser :L26 and conduit 1112. The discharge from the upper end of slide valve b3 iiows through conduit n.15', releaser u1B and conduit a15". The discharge from the upper end of distributor valve a3 flows through conduit 1315', distributor Z224 and conduit b15". The discharge from the lower end of slide valve c3 passes through conduit 1:12', distributor C24 and conduit 012" and the discharge from the lower end of distributor slide valve a3 passes through conduit c15, releaser C28 and conduit c15- As indicated in the drawings, all of the releasers are similarly constructed and the plungers thereof are spring pressed to a position in which the discharge from the releasers to the return pipe communicates with the inlet to the releaser from the associated distributing valve chamber. In other words, the resilient means urges the plungers to a position that the control bore of the releaser is in communication with the exhaust bore thereof, the inlet bore in communicationV with the pressure line P being normally closed.

The circuit of the pump p also includes a disder b2 through piping b6 to raise piston b1.

4 charge valve or bypass I8 of a known type so as to prevent damage to the pump when the shutoff valve I1 is closed.

In the drawing the piston 0.1 is at the lower point of its stroke. The slide valve a1 of the distributor a4 has just reached the upper point of its stroke so that the circular groove a5 on the slide valve a3 is in communication with the pressure line P extending parallel with conduit b15". The fluid in cylinder a2 can escape therefrom through conduit a7, chamber as in the slide valve and return to the tank 1* through conduit a9 and return pipe A.

With piston a1 at the lower point of its stroke the cam a2o has contacted and depressed plunger (123 ofthe releaser w24 so that fluid under pressure can flow through the releaser out through conduit am' into the upper end of distributing cylinder c4 to act against the piston on the upper side of the distributing slide valve c3, the upward movement of piston c1 having caused the cam c22 to depress plunger c2'1 to permit fluid to iiow from the pressure source through releaser C28 and conduit 015' to the under side of the piston on the lower end of distributing slide valve a4.

When the pressure uid has raised piston a1 so that it reaches the upper limit of its stroke, the cam m22 will contact and depress plunger a2" of releaser c211 to permit fluid under pressure to flow from piping P through the releaser c11B into conduit n.15', thence to the upper side of the piston on the upper end of distributing slide valve b4 associated with the piston b1. This piston b1 being at the high point of its stroke in cylinder b2, the slide valve b3 of distributor b1 is also at the upper end of its stroke so that fluid under pressure has passed through the groove b5 into cylin- As indicated, when the pressure fluid controlled by releaser L28 flows through conduit 115' the slide valve b4 will be moved downward and groove i116 will be placed in communication with conduit bI to permit pressure iiuid entering the distributor b1 from line P to force the piston b1 downwardly.

When the piston b1 has reached the lower point.

of its stroke the cam b2 will engage and depress plunger Z323 of releaser i324 so that fluid under pressure will flow through this releaser, thence through conduit Z215' to the upper end of distributor a;4 for actuating the same downwardly.

The piston c1 is also at the upper end of its stroke in cylinder c2. The slide valve c3 is at the top of its stroke in distributor c1 so that the pressure uid has passed through the distributor, the groove c5 and the piping c6 to the under side of piston c1. As previously indicated, the downward stroke of the piston a1 has actuated releaser a21 so that iiuid will now flow into distributor c4 at the top, and in the drawing the slide valve c3 is about to be moved downwardly so that the circular groove o16 will serve for the passage of pressure fluid from the source into piping c'I to the upper side of piston c1 to lower the same.

When the piston c1 reaches the lower point of its stroke the cam 02 will contact and depress plunger o23 of releaser c24 permitting pressure fluid to iiow through this releaser 024 and conduit C12 to the under side of the piston on the lower end of distributing slide valve c3 to raise this valve.

Briefly, therefore, in the drawing the piston c1 has just reached the high point of its stroke permitted iiuid under pressure to flow through assets-s l conduit C', resulting in the upward pressure 'displacement of slide valve a3 of the distributor a4. Fluid flow from the pressure source through groove a5 and conduit a6 will immediately move the 'piston a1 upwardly.

When the piston u1 reaches its upper position cam a22 will displace plunger L27 permitting fluid under pressure to ow through releaser a22 and conduit a15 into the upper end of distributor b4 to displace distributor valve b5 downwardly to place groove b1s in registry with conduit b7 4to permit the lowering of piston b1 which, upon reaching its lower position through the cooperation of cam Z120 with plunger Z123 will permit fluid under pressure to flow through releaser b24 and conduit Z915' to the upper end of distributor a4 so that the resulting displacement of slide Vvalve a3 will permit pressure fluid to move piston a1 downwardly.

As indicated in the drawing, the downward movement of piston a1 controls slide valves b3 and c3 successively, the first shortly before the end of the downward stroke and the second at the end of the downward stroke. While the support member (1,12 is moving downwardly with piston a1 the cam (121 engages and depresses plunger a25 of releaser 126. As shown in the drawings, this releaser is displaced laterally out of alignment with the other two releasers associated with cylinder a2 and the cam a21 which is pivoted to the cylinder projects outwardly of support L19 a distance greater than the extent of projection of cams a and a22 respectively. Cam 0,21 is provided with a tongue on its rear side which limits the pivoting movement thereof so that it cannot pivot upwardly beyond the position shown in the drawing and a spring urges the same to the position illustrated. On downward movement it is obvious that cam a21 actuates the plunger c25, thus permitting pressure uid to flow through releaser a26 into conduit 1112 to the under side of distributing slide valve b3 for raising distributing valve b3 to permit fluid under pressure to enter cylinder b2 to raise piston b1. As previously set forth, the continued downward movement of piston a1 effects the cooperation between cam w20 and plunger 0,23 to permit the pressure fluid to now into the upper end of distributor c4 displacing the valve c3 permitting pressure fluid to lower piston c1. lThe piston c1 on arriving at its lower position actuates plunger C22 to eiect the raising of slide valve c3 and thus the return or upward stroke of the piston c1. When piston c3 reaches its upper position it again actuates the plunger C22 to permit fluid to again ilow through conduit 015 to the lower side of distributor a4 for further actuation of the slide valve a3 and resulting in upward displacement of the piston a1.

As described, the yieldable cam a21 is employed to effect the upward actuation of distributor valve b2 before the downward movement of distributor valve c3. This stop must be yieldable in one direction of movement of the pitston a1 since otherwise the passage of liquid under pressure would occur twice, once when the piston a1 comes down and again when it rises when the order of the actuation of the distributing slide valves would be disrupted.

As illustrated, on the upward movement of piston a1 from the position shown, the cam 11,21 will rock about the axis a29 and not depress plunger a25.

It is also to be noted that in the releasers which are inthe depressed position, which as illustrated isvthe case for the -ilea'si corresponding to the position of the piston a1 at its lower position and for the releaser corresponding to the piston c1 at its higher position the liquid under pressure is admitted through one of the-,ports of the releaser for passage therethrough in order to actuate each distributor controlled by the said releasers.

On the contrary, the third port of said releasers Awhich-is connected with the return pipe for returning the liquid to the tank, is closed during the veffective action of said releasers.

But as soon as this effective action ceases, that is to say as soon as a stop cam no longer engages the plunger of a releaser the inlet passage for the liquid under pressure is immediately closed while the passage for the return of liquid to the tank is immediately opened by the spring embodied with each releaser.

This is necessary in order for the liquid which is at l,one end of the slide-Valves on the thrust side to escape when the direction of movement of the said slide-valves changes, so as not to oppose the movement of translation of the valves. When-this change in the direction occurs the fluid which is forced back passes again through the releaser connected with the distributor under consideration in order to then return to the tank.

For stopping a machine controlled by actuating pistons themselves controlled by the device according to this invention it will be suflicient to interrupt the circuit 'of the fluid under pressure by means of the valve I1.

For starting again it will also be sufficient to open said valve, the motions then beginning to work without the intervention of any actuating organ with the exception of the pump or any other source of pressure delivering the uid under pressure to the actuating pistons.

The velocity at which the strokes of all driving pistons are performed, can be controlled by throttling the now of the fluid under pressure by means` of the valve l1.

Through an examination of the preceding explanations land the figure of the drawing, it is apparent:

1. That the control of the movement of the pistons is effectively obtained as disclosed in the above-mentioned co-pending application but that the omission of the ports on the piston rods avoids any loss of fluid under pressure, more particularly through the openings provided in the upper part of said piston rods.

2. That in case it is necessary that an actuating piston controls the movement of another piston before the actuating piston completes its own forward stroke or return stroke, the new arrangement cannot release the desired movement twice since the releasing cam yields when the direction of the movement of translation of the support carrying the cam reverses.

3. Lastly, and as in the above-mentioned application if any incident locks any one of the actuating pistons none of the other actuating pistons incorporated with the same machine can start again after having accomplished its stroke.

I claim:

l. In an hydraulic control system adapted to control movable parts, the combination of a source of uid under pressure having a delivery conduit, controlling means in the delivery conduit of said source, an exhaust conduit, a plurality of hydraulic motors each comprising a working cylinder having ports at its ends, a driving piston reciprocable in each of said working cylinders, a piston rod fast to each of said pistons and to lthe movable part to 'be controlled; a plurality of releasers each including an inlet bore connected with said delivery conduit, an exhaust bore connected with said exhaust conduit, a control bore, movable means for connecting said control bore respectively with said inlet bore and said exhaust bore, and resilient means urging said movable means towards the position 'connecting said control bore with said exhaust bore; cam members fast to said piston rods and adapted to act upontheir associated movable means at a given point of the stroke of said driving pistons; a plurality of slide valves each adapted to connect the ports of its associated cylinder respectively ivith said delivery conduit and said exhaust conduit, an` actuating cylinder having an orifice in the bottom thereof disposed on each side of each slide valve, each actuating cylinder having a slidable piston therein fast to its associated slide valve, and transmitting conduits interconnecting V-said control bore to said orifices in a given order following the sequence of operations to be performed.

2. A hydraulic control system as claimed in claim 1, in which the control bore of at least one releaser is connected to` the bottom orice of an actuating cylinder of the slide valve associated with the working cylinder whose piston rod is adapted to act upon the movable means or' said releaser.

3. In an hydraulic control system adapted to control movable parts the combination of a source of duid under pressure having a delivery conduit, controlling means in the delivery conduit of said source, an exhaust conduit, a plurality of hydraulic motors each comprising a Working cylinder having ports at its ends, a driving piston reciprocable in each of said working cylinders, a piston rod fast to each of said pistons and to the movable part to be controlled; a plurality of releasers each including an inlet bore connected with said delivery conduit, an exhaust bore connected with said exhaust conduit, a control bore, movable means for connecting said control bore respectively with said inlet bore and said exhaust bore, and resilient means urging said movable means towards the position connecting said control bore with said exhaust bore; cam members fast to said piston rods and adapted to act upon their associated movable means at a given point of the stroke of said driving pistons; at least one cam member adapted to act upon at least one of the movable means in one direction of the movement of the corresponding driving piston. but to be tilted yieldingly to an inactive position in the other direction of the movement of the piston, a plurality of pressure operated slide valves, each controlling connection between the ports of each Working cylinder and the delivery and exhaust conduits; each slide valve having an actuating cylinder disposed on opposite sides thereof, each actuating cylinder having an orilice in the bottom thereof, and transmitting conduits interconnecting said control ocres to said orifices in a given order following the sequence of operations to be performed.

4, A hydraulic control system as claimed in claim'l in which the Working cylinders are arranged in series and include a first and a last cylinder' and the control bore of one releaser of the last Working cylinder is connected to the orifice of an actuating cylinder of the slide valve belonging to the first Working cylinder so that the sequence of motions is automatically repeated. r

RENE DETREZ.

REFERENCES CITED The following reerences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,179,195 Le Brocq Apr. 11, 1916 1,870,503 Gruetter Aug. 9, 1932 1,905,065 Scholl Apr, 25, 1933 1,994,974 Wiedmann Mar. 19, 1935 2,054,296 Merrill Sept. 15, 1936 

